How to Save Money Using a Variable Speed Motor

Written by:  Danny Rhodehamel
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 (2.88 OUT OF 5 STARS ON 12 RATINGS)

Many people are switching to variable speed motors or pumps to save around 75% in their electric bill. If you are paying $800 a year now with a single speed motor, you can drop that cost to $200 a year with a variable speed motor (Based on $0.15/KWH - 20,000 gallon pool). NOTE: PRICES SHOWN MAY HAVE BEEN REDUCED SINCE THIS GUIDE WAS WRITTEN. SEE PRODUCT PAGE FOR CURRENT PRICES.

Tips & Warnings

Step by Step

Step 1

Parts of a Variable Speed Motor - A typical variable speed (VS) motor has three major parts: the motor itself, the drive that is bolted on top of the motor and the controller that sits on top of the drive. The drive provides electrical lines to the motor and contains the circuit boards used to control the motor. The controller has has a panel of buttons and a display that allow the user to program time and speed commands to the drive. In many cases the controller can be taken off the drive and mounted on a wall for easier accessibility to the panel.

Step 2

Overview of Common Features - Variable speed motors on the market today have many features in common. They offer up to 85% savings in operational costs with an average savings of 75% depending on your pool features. Most are wired for 230V and can run between 600 and 3450 RPM. Their max Total Horse Power (THP) is in the range of 2.3 to 3.45 HP. All have integrated programmable timers mounted on the top of the motor. Most can be programmed for up to 8 different speeds in 8 different time slots. All variable speed motors use permanent magnets technology in place of coiled wire used in standard induction single speed motors. All variable speed motors have a Totally Enclosed Fan Cooled (TEFC) design. These motors also run much quieter at full speed. At the lower speed you can hardly hear them at all.

Step 3

TEFC- Totally Enclosed Fan Cooled (TEFC) motors keep water and bugs out which prolongs their life to 3 times the life of a standard induction motor. The motor can be totally enclosed because the permanent magnet technology allows these motors to run much cooler and quieter than the standard induction motors.

Step 4

Operation - Each of the various functions of your pool requires a minimum water flow to operate. You would set your pump to run at the lowest RPMs required to generate the minimum required water flow. The filtrations system can operate at low water flow with typical motor speeds around 1000 RPM or less depending on the size of your pool and how long you want to run the pump. Suction cleaners typically run at around 2200-2400 RPM. Heaters require 20 to 40 Gallons Per Minute (GPM) so might run at around half speed or a little higher. You would probably want to run your Spa at up to full speed, 3450, for maximum effect. The speed required for any water features like waterfalls, bubblers, and laminars would depend on the desired height or projection.

Step 5

Setting Operational RPMs - Determining the minimum speed required to operate each feature is easy. For example, a heater will shut off if it doesn't have sufficient water flow (GFM) to prevent overheating. To determine where your heater shuts off for your particular pool system, set the pump's speed at a low rate of RPM and then increment it in steps until the heater kicks on. Add 50 RPM to account for system variations and you have your minimum RPM for heater operation. If you have a solar heating system, do the same process and check the RPM at which the cavitation in the pump stops. If the water flow is not sufficient to supply your pipes on the roof, the water flowing down the pipes by gravity may get ahead of the water coming up and you will start to get air in your lines. For a suction cleaner, look for optimum performance in the cleaner.

Step 6

Typical program - The current variable pumps have a digital control interface mounted on top of the motor from which you can program your different speeds and run times. A program for a typical pool might look like this: Suction cleaner - run at 2400 for 2 hours; Filtration - run at 1200 RPM for 16 hours; Spa run at 3450 for 2 hours or on demand. Most pumps have manual overrides to change settings temporarily.

Step 7

Savings - So where's the saving? A basic law in physics says that if you reduce the RPM of a motor by 1/2, you reduce the energy required to move that water to 1/8 the full speed energy. So, if it costs $2.20 a day to run my single speed motor for 8 hours, it would only cost 1/8 of that or $0.28 to run a variable speed motor for 8 hours. But, you say, where's the savings if I have to run the pump twice as long because I'm only moving half the water at half speed? Running a variable speed motor at half speed for 16 hours would cost twice the cost for 8 hours or $0.55 / day. That's still a huge savings of 75%.

Step 8

Cost for Typical Pool Program - Costing out the typical pool program provided above looks like this: If I run the filtration system at 1200 RPM instead of 1725 RPM (half speed), my energy cost drops even further to around 5%. Using the numbers above, 5% of $2.20 is $0.11 for 8 hours or a total of $0.22 for 16 hours. To run a suction cleaner at 2400 drops energy cost to about 40% of full RPM costs. 40% of $2.20 is $0.88 for 8 hours or a total of $0.22 for 2 hours. Running the Spa at full RPM (3450) for 2 hours would cost 1/4 of $2.20 or $0.55. Comparing the total costs: Single speed motor - 8 hours of filtration and cleaning and 2 hours of Spa costs $2.20 + $0.55 or a total of $2.75. Variable speed motor - 16 hours of filtration, 2 hours of suction cleaning and 2 hours of Spa costs $0.22 + $0.22 + $0.55 or a total of $0.99. That's a savings of 65% even with running the Spa at full speed for 2 hours. Without the Spa, you would save 80% ($0.44/$2.20). Note that these cost numbers are only representative and will vary based on your pool size and electricity costs, but the savings percentages are the same regardless of actual costs.

Step 9

Payback - How do you justify the cost of a variable speed pump or motor? A variable speed pump costs about $1200 or two to three times the initial cost of a comparable single speed pump. If you are just replacing the motor, a variable speed motor costs about $800. The cost savings is in operational costs. If you currently spend $800 a year, at 75% reduced operation costs, you will be spending $200 a year or $600 less a year. You could pay off the difference in cost in a little more than a year for the pump and somewhat under a year for just the motor. Plus these motors are sealed and built to last 3 times longer than the current single speed motors. You would have to buy 3 single speed replacement motors for every variable speed motor.

Step 10

GPM requirements - We touched on this above but a common concern with variable speed pumps is insufficient water flow to operate some features like a heater and a suction cleaner. The argument goes - If I have to reduce the motor's RPM and water flow to get meaningful savings, I can't operate some pool function. If I have to operate at higher RPMs, I lose all my saving. You saw the savings above with a suction cleaner. Let's add in the heater.

Step 11

Costs of running filtration with a suction cleaner and a heater. – If I run the heater at 2400 RPM for 8 hours a day to heat the pool at something above the required 40 GPM, I could run the cleaner for 2 hours in that same time slot. Then I would have to run the pump for another 4 hours for filtration at 1200 RPM to compensate for the lower flow rate. From the calculations in Step 7, my cost for 4 hours of filtration is $0.06 (8 hours was $0.11). Running the pump at 2400 for the heater/cleaner uses about 40% of the energy to run at full speed. From the numbers above, if it costs $2.20 to run a single speed (SS) pump for 8 hours, if will cost $40% of $2.20 or $0.88 to run the VS pump at 2400 RPM for 8 hours. The total cost of running the VS pump is $0.94 ($0.06+$0.88) for 12 hours. That’s a % savings of 57%.during the months that you have to run a heater. Note that this is just the cost of running the pump to circulate the water through the heater. This cost does not include the cost of fueling the heater.

Step 12

State Regulations - States are starting to regulate energy usage on pools. At some point we may all have to change over to variable pumps. California's Title 20 regulation requires that pumps > 1 THP must be 2-speed or variable speed and must have a control to default to low speed after being in high speed of an extended time. Florida just passed a similar regulation in March 2012, HB 849.

Step 13

Automatic adaptability - A single variable speed (VS) motor can be used to replace any size single or dual speed motor from 3/4 HP to 2.5 HP. By design a VS motor automatically adjusts to required torque. If you replace a 1 1/2 HP single speed motor with a 2.5 max HP VS motor, the VS motor will sense that the pumps wet end has an impeller for a 1 1/2 HP, and the motor will only use the energy required to drive that 1 1/2 HP impeller. Even at full speed, 3450 RPM, the VS motor will not exceed the energy required for a single 1 1/2 HP pump. In terms of costs, the cost of running a replacement 2.5 HP VS motor at 3450 RPM is no higher than the cost of the replaced 1 1/2 HP motor. In fact due to the permanent magnet design of the VS motor, the cost will be 85% cheaper at full speed.

Step 14

Comparison of pumps - As I mentioned above, most of the variable speed pumps on the market or just coming out now, have similar features. The following is a discussion of some of the unique features of each.

Step 15

Hayward Ecostar - Priced at $1269. Has a SVRS option for $1469. A 3 HP variable pump with a range of 600 to 3450 RPM. Can program 8 different speeds. One of the most efficient pumps based on 30 years of hydraulic design (volute, impeller). The controller and drive are mounted on the top of the motor. The controller can be removed and mounted on a wall up to 500' away. This drive can be integrated with Hayward's E-Command 4 automated control systems or most other manufacturers automated control systems. See EcoStar or EcoStar with SVRS for InyoPools links to these pumps.

Step 16

Hayward Ecostar Controller -

Step 17

Pentair Intelliflo - Three models are offered: two Variable Speed (VS) pumps; the 3050 for $930, the 3050 with SRVS for $1130; and one Variable Flow (VF)Pump for $1365. The VS pumps are programmed for up to 8 separate speeds and times. The VF pump is programmed to maintain up to 8 separate flow rates (GPM). Further, the VF pump can automatically calculate and program the minimum flow rate required for each task - filtering, heating, cleaning, spa jets, water features and more. All are 3 HP (3.95 THP) and operate in a range of 450-3450 RPM. The controller/drive is mounted on the top of the motor. There is no option with this pump to remove and mount the controller on a wall, but the drive can be wired to operate with Pentair's automated control systems including IntelliTouch, EasyTouch and SunTouch. It is not compatible with other manufacturers automated control systems. The Pentair Intelliflo pump uses its own Pentair designed motor and is not compatible with other motors for replacement. See IntelliFlo VS 3050 Pump or IntelliFlo VS Pump with SVRS or IntelliFlo VF Pump for InyoPools links to these pumps.

Step 18

Pentair Intelliflo Controller -

Step 19

Jandy VS FloPro - NEW - Priced at $TBD. A 2.0 THP variable speed pump with an operating range of 600-3450 RPM. The controller is plugged into the drive on top of the motor and can be mounted on a wall up to 20' away. The drive has two timers and 8 programmable speeds so two functions can be programmed to run automatically every day and 6 other functions can be manually initiated to run for a programmed amount of time. This pump is a smaller sized pump that the Jandy ePump discussed below. It is designed to handle less GPM for pools with limited water features. Pump Base Kit allows for easy retrofit replacement for the following manufacturer/models: Hayward Super Pumps; Pentair WhisperFlo and SuperFlo; Sta-Rite Dyna-Glas, DuraGlas, and Max-E-Pro; and Jandy PlusHP and MaxHP.

Step 20

Jandy VS FloPro Controller -

Step 21

Jandy ePump - Two pumps offered: JPR1.5 with a Total HP (THP) of 2.2 for $900, and JPR2.0 with a THP of 2.27 for $1091. Both operate in the range of 600-3450 RPM. The controller is the same on used on the Jandy FloPro discussed above. For this pump, however, the controller is a separate cost. If you choose not to purchase the controller, the ePump can be controlled by integrating it with the following automated pool control system. iAquaLink, Aqualink Touch, and Aqualink RS One Touch, and Aqualink PDA systems. See Jandy ePump VS 1.5 HP Pump or Jandy ePump VS 2.0 HP Pump for InyoPools' links to these pumps.

Step 22

Jandy ePump Controller - Not included with the pump. Priced separately at $388. See Jandy ePump Controller for InyoPools' link to this product.

Step 23

Speck Badu EcoMV - Two models offered: - EcoMV/72-V, $1320, 2.5 THP: and EconMV/72V1, #1381, 3.5 THP with SVRS. Both operate between 600 and 3450 RPM. The Controller mounted on top of the motor with the drive can be rotated 360 degrees for accessibility or can be mounted away from the pump. The pump can be programmed for 2 speeds / day Monday thru Friday and 3 speeds /day on Saturday and Sunday. Unique flow around basket design reduces blockages. See Speck Badu EcoMV Pump or Speck Badu EcoMV Pump with SVRS for InyoPools' links to these pumps.

Step 24

Speck Badu EcoMV Controller -

Step 25

Century VGreen Motors (9ECM27) - Priced at $699. - MOTOR ONLY with controller and drive. Century purchased AO Smith recently and is now the leading pump motor manufacturer. Many manufacturers used AO Smith induction motors in their pumps and this is also true of the newer variable speed motors. If you buy a new variable speed pump, you will likely be buying a Century motor. The Century V-Green motor is available with either a square or round interface to fit most pumps. It has 2.77 THP and can operate between 600 and 3450 RPM. The motor comes with the controller mounted on the top of the motor but this controller can be installed on a wall with the purchase of a separate kit. The drive is currently not compatible with any automated control system. See Century VGreen Motor with Sq. Flange or Century VGreen Motor with C Face (round for InyoPools' links to the two versions of this pump.

Step 26

Century VGreen Controller -

Step 27

Waterway Econo-Flo - Priced at $TBD. This pump uses the Century VGreen motor described above so it has all its features and operational characteristics.

Step 28

Waterway Econo-Flo Controller - Same as the Century VGreen Controller shown above.

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Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.